Ha Seon-jae

Mantis, an ace assassin, returns to the contract killer industry after a hiatus, encountering his trainee friend Jae-yi and a retired legendary killer Dok-go, who now runs the organization.

Sun Woo comes from a poor family background. She was once a promising Taekwondo athlete, but she now works part-time jobs to support herself. One day, she is is selected to become the stand-in for Ji Yeon due to their similar appearance. Ji Yeon is the granddaughter of Beomhan Construction Company's chairman. She was the driver of a fatal hit-and-run car accident. Sun Woo must play Ji Yeon in front of the public and media. Meanwhile, Sun Woo becomes the target of Ho Joong’s hostility. Ho Joong is Ji Yeon’s stepbrother and he has an inferiority complex over Ji Yeon. He wants to become the successor to Beomhan Construction Company.

A college student navigates life and school while dealing with a unique predicament — he's living with a beautiful former K-pop sensation.